I can't speak to the fx shots, but the live action screenshots show a much more realistic and pleasing color palette to my eye. Look at Spock's jacket, for example, in the Engineering shot. The blu ray reveals the accurate slightly marroon shade of the uniforms. By comparison, the DVD looks like a tv with the color cranked up. And the bridge shot, the bridge walls are restored to a proper neutral grey balanceas well.

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"Even with all its blemishes, Trek XI still teabags the bloated corpses that were Insurrection and Nemesis and managed to make Trek fun again." - Sheep